Acid Dipping Engines

[spewey at comcast.net (Spewey)]

Brian Haygood wrote:
> What kind of acid is used to clean engines and such?  Put more
> generally, what kinds of acids will eat everything on the planet
> except steel and aluminum?

I successfully cleaned my 2-cylinder river-water-cooled sailboat 
engine's crusty water passages with phosphoric acid that I borrowed from 
the chem lab I was working in.  Muriatic (30% HCl) is more likely to be 
available to the common man as it is used to clean pools and concrete.

Also:

"Technical quality HCl at typically 18% concentration is the most 
commonly used pickling agent for the pickling of carbon steel grades."

http://en.wikipedia.org/wiki/Hydrochloric_acid

And:

"Final treatment of iron and steel products before onward sale into 
manufacturing includes pickling in strong mineral acid to remove rust 
and prepare the surface for tin or chromium plating or for other surface 
treatments such as galvanization or painting. The two acids commonly 
used are hydrochloric acid and sulphuric acid."

http://en.wikipedia.org/wiki/Pickling#Other_uses_of_the_word_.22pickle.22